Wind-Induced Fatigue Analysis of High-Rise Steel Structures Using Equivalent Structural Stress Method

Zhao Fang,Sheng Shen,Aiqun Li,Wanrun Li

doi:10.3390/app7010071

Abstract

Welded beam-to-column connections of high-rise steel structures are susceptive to fatigue damage under wind loading. However, most fatigue assessments in the field of civil engineering are mainly based on nominal stress or hot spot stress theories, which has the disadvantage of dependence on the meshing styles and massive curves selected. To address this problem, in this paper, the equivalent structural stress method with advantages of mesh-insensitive quality and capability of unifying different stress-life curves (S-N curves) into one is introduced to the wind-induced fatigue assessment of a large-scale complicated high-rise steel structure. The multi-scale finite element model is established and the corresponding wind loading is simulated. Fatigue life assessments using equivalent structural stress method, hot spot stress method and nominal stress method are performed, and the results are verified and comparisons are made. The mesh-insensitive quality is also verified. The results show that the lateral weld toe of the butt weld connecting the beam flange plate and the column is the location where fatigue damage most likely happens. Nominal stress method considers fatigue assessment of welds in a more global way by averaging all the stress on the weld section while in equivalent structural stress method and hot spot method local stress concentration can be taken into account more precisely.

Highlights

Wind loading is a major loading to high-rise structures, which causes vibration but may bring about fatigue problems as well, for the fluctuating wind as a random loading can be regarded as a sort of cycle loading for high-rise structures and may cause fatigue crack initiation in components where large stress concentration exists and leads to fatigue failure
8.074 ×104 In Table 2, it can be seen that the fatigue damage of the fillet weld connecting the web plate and the column is much smaller than that of the butt weld connecting the upper beam flange plate and column, which means in high-rise steel braced frame structure the butt weld connecting the upper beam flange plate and column is more dangerous in regards to fatigue damage
Accordingtotothe theresults resultsobtained obtainedabove, above,ititcan canbe befound foundthat thatwith withthe thedecreasing decreasingelement elementsize size dimension dimensionand andthe theuse useof ofhigh highorder orderelements, elements,the theeffective effectiveequivalent equivalentstructural structuralstress stressrange rangeand and fatigue life assessment results based on equivalent structural stress method keep almost invariant, fatigue life assessment results based on equivalent structural stress method keep almost invariant, which whichverifies verifiesthat thatthe theequivalent equivalentstructural structuralstress stress method method is is mesh‐insensitive

Summary

Introduction

Wind loading is a major loading to high-rise structures, which causes vibration but may bring about fatigue problems as well, for the fluctuating wind as a random loading can be regarded as a sort of cycle loading for high-rise structures and may cause fatigue crack initiation in components where large stress concentration exists and leads to fatigue failure. Several cases of wind-induced fatigue failure of steel mast structures have been found in history [1]. As to high-rise steel frame structures whose beam-to-column connections are mostly welded and local stress concentration inevitably exists, fatigue cracks are prone to initiate near welded joints in beam-to-column connections, which certainly brings potential danger of fatigue failure.

Methods

Results

Conclusion